Behind The Scenes Of That 'Game Of Thrones' White Walker Battle With Wilding Birgitte Hjort Sorensen

On the massive Game of Thrones, it's easy to forget who characters are if they only appear in an episode or two — hell, with so many cast members, it's easy to forget the ones you've been watching all series long. If you saw the Season 5 episode "Hardhome," though, then you definitely remember the character of Karsi. The Wildling-turned-White Walker is pretty unforgettable; seeing those ice blue, zombified eyes alight as she became part of the Night's King's army was one of the eeriest sights of the season. Yet for the actress who plays her, "eerie" perhaps isn't the right word to describe her behind-the-scenes Game of Thronesexperience. So what was it really like to film that crazy, surreal battle between good and evil, Night's Watch, Wildlings, and White Walkers?

"I just had the best time, chopping up those guys," Birgitte Hjort Sorensen tells Bustle. "It was so much fun."

A Game of Thrones battle, fun? Apparently, yes — not to mention very, very, cold, Sorensen quickly adds. For the huge scene in "Hardhome," the series shot outside Belfast, where the crew built "this incredible, almost medieval village," the actress says. Employing hundreds of extras and its already-large ensemble, the scene was unbelievable to witness, and even more so for its actors.

Says Sorensen, "It could be a little overwhelming with four cameras and a snow machine and a bunch of dead guys coming at you."

It must not have helped that until joining the show, Sorensen, while familiar with Thrones, didn't understand the full extent of its size, both in popularity and literal space needed to film many of its scenes.

"I hadn’t really realized until I walked on set how massive a show it is," she says, adding that the experience was "mindblowing."

Although Sorensen's Karsi fit right in with Thrones' cast of characters, being a newcomer to Westeros must've been difficult for the actress; best known for roles in the Danish TV show Borgenand this summer's Pitch Perfect 2, Sorensen was no stranger to acting, but nothing she'd done before was as epic and fantastical as Thrones.

"It was something very different from what I’d done before," she says. "But I felt like all the makeup, all the costumes, all the stuff around me just helped build the illusion that I needed to believe... I think the challenge, for me, at least, as an actor, with doing fantasy stuff is it can feel remote from yourself. You feel like, how can I relate to this fantasy world with dragons and zombies? But when so much time and care is put into the surroundings, it makes the illusion very easy to believe."

At the end of "Hardhome," viewers saw Jon Snow (Kit Harington) sail away from the scene, terrified and overwhelmed by the White Walker army that had just formed. All Thrones fans know what happened in the following two episodes; betrayed by his men, who believe he's led them into defeat, Jon is stabbed repeatedly, and left for dead. The question of Jon Snow's fate has been a heated debate among Thrones fans since Season 5's end, and everyone has a theory about if he's dead, alive, or some variation in-between. But what do Thrones' actors think about their co-star's potential return?

"What I know of Game of Thrones is that anything can happen," says Sorensen. "I certainly hope in some way that he can come back, I love Jon Snow! But I have no idea."

As for her own fate on the show, the actress says she truly doesn't know if she'll return ("it’s better to think about the job you’re involved with than the one that possibly lies ahead," she insists). Here's hoping Karsi's only getting started with her White Walker reign — it may mean bad things for The Night's Watch and the rest of Westeros, but it'd make for great entertainment for Thrones' loyal viewers.

Need more Thrones in your life before Season 6? Watch Bustle explain why the R+L=J theory is totally real: